The long-range goal of this project is to restore functional movement to low-functioning stroke patients using a novel therapeutic regimen and robotic device called "AMES," an acronym for Assisted Movement with Enhanced Sensation. In AMES-as it is currently used-the patient's affected limb is moved cyclically with the AMES robotic device while the sensation of motion is enhanced by an AMES muscle vibrator applied to the antagonist muscle(s). The patient simultaneously assists with the imposed movement using biofeedback of voluntary joint torque. In a Phase I clinical trial (Cordo 2008), AMES was determined to be effective at restoring functional movement in both upper and lower extremities of low-functioning chronic stroke subjects (>1 yr post-stroke), several of which were plegic. At enrollment, most of these subjects had no more than 30% of normal strength in the affected arm or leg. Despite this success at treating these highly disabled stroke subjects, AMES treatment usually did not restore functional movement at the fingers, wrist, or ankle if the joint was plegic. EMG recordings were taken of these subjects during AMES therapy, and all retained the ability to activate voluntarily their 'plegic'muscles. However, because this muscle activity was so weak, and because it competed with antagonistic co-contraction, these individuals were unable to counteract the opposing forces in order to move the joint. The goal of this proposed project is to incorporate EMG biofeedback into the AMES device and regimen for plegic stroke patients, as an alternative to joint torque biofeedback when no joint torque can be produced. Phase I of this project focused on eliminating electrical and mechanical noise in EMG recordings caused by the tendon vibrators, and on prototyping software to test the feasibility of combining the AMES regimen with EMG biofeedback. The goal of Phase II is to further develop the hardware and software associated with EMG biofeedback and muscle vibration, and to test the efficacy of AMES with EMG biofeedback on stroke patients with hand extensor plegia. There are 3 specific aims proposed in this Phase II application. Specific Aim 1 is to develop further the presentation of EMG biofeedback on the AMES device by designing and integrating a 2-channel EMG amplifier into the device and making the biofeedback more engaging to patients. Specific Aim 2 is to develop new, more reliable and user-friendly technology for muscle vibration, including the vibrator itself and its positioning mechanism. Specific Aim 3 is to test the efficacy of AMES with EMG biofeedback at 3 sites (Emory University School of Medicine, Oregon Health &Sciences University, and the Rehabilitation Institute of Chicago) in a randomized, controlled clinical study of 64 chronic plegic stroke patients. PUBLIC HEALTH RELEVANCE: This project addresses a sub-group of chronic stroke patients with hand plegia in extension, but who retain some ability to activate voluntarily the 'plegic'muscles. Our earlier studies suggest that as many as a third of the approximately 4 million stroke victims in the US with chronic motor disabilities have hand and/or foot plegia. The proposed technology is designed to reverse co-contraction at plegic joints and to restore functional movement. This Phase II project will test the efficacy of using biofeedback to retrain muscles in conjunction with a new therapeutic regimen called "AMES," and to bring the AMES therapy device to the threshold of commercialization.